Non-Invasive Analysis of Green Stone Pieces from Tomb 1 of Chiapa de Corzo, Chiapas

Abstract

Recently, a team of archaeologists discovered the existence of the oldest burial in a pyramid known to date in Mesoamerica. The tomb, referred to as Tomb 1, was discovered in Chiapa de Corzo, Chiapas, Mexico. In here, two skeletons were excavated along with a rich offering of green stone pieces, indicating their elite origin. The burial dresses consist of various necklaces, bracelets, belts, and anklets from which some beads were carved in the shape of gourds, monkeys, and alligators. Here we present a full, integrated methodology based on a variety of non-invasive and non-destructive analytical techniques, such as X-ray fluorescence (XRF), Raman, and Fourier Transform infrared (FT-IR) spectroscopy. These techniques are used to characterize and identify the minerals which were found in these burials. This information contributes not only to conservation and restoration purposes, but also gives more insights on the green stone (jadeite and other minerals) trading networks between different cultures in south Mesoamerica in the Pre-Classic period (c.a. 750 – 700 B. C.).

Molecular and X-ray Spectroscopies for Noninvasive Characterization of Mayan Green Stones from Bonampak, Chiapas

“…The 532 nm laser was fundamental for confirming the presence of amazonite, a mineral with no geological sources reported in the Mesoamerican region, but nonetheless, commonly present in offerings of the area. 20,21 The latter may imply so far the existence of trading routes between the Mayan cities and the area now occupied by the states of Colorado, Arizona, and New Mexico, USA, where the known amazonite (microcline) sources are located. Future work will require the comparison of geological samples from these regions and the archaeological data to test the provenance of the raw materials to manufacture these amazonite items.…”

“…However, the XRF results of samples from these two sources placed them together in one of the groups formed, suggesting that there are at least three more sources of jade in Mesoamerica use by the Maya, something that has been observed in studies from other sites in this region. 20,21…”

“…These results contrast with other analyses were different objects discovered in the burials were manufactured in particular workshops 48 with raw materials from specific sources. 20,21 An interpretation for the clustering observed in the raw materials in the artifacts of the tomb of Room 2 is that pieces from other objects may have been reused to compose the offering. Another possibility is that the same mineral sources were exploited during the whole period of time when these artifacts were manufactured.…”

“…In Mexico, a combination of portable Fourier transform infrared (FT-IR), Raman, and XRF devices has been previously used for the study of Mesoamerican objects. 19–22 Raman and FT-IR spectroscopies detect vibrational modes of molecular bonds, identifying different composites. X-ray fluorescence is useful for elemental identification and the information obtained helps prove hypothesis about manufacture, origin, or conservation of archaeological objects.…”

The mirrors from Chiapa de Corzo: an early example for the Classic pyrite mirrors?

“…The offerings of Tomb 1—which included numerous jade ornaments, pearls, shells, pyrite mirrors, amber, quartz, and turquoise beads, as well as ceramics, hematite, and obsidian pieces—totaled 3,728 elements and provide information of great relevance for understanding cultural relationships and possible exchange routes. The mineralogical analyses of these objects, using X-ray fluorescence (XRF) and infrared (IR) and Raman spectroscopy, were carried out by members of the Institute of Physics (Instituto de Física) at the Universidad Nacional Autónoma de México (UNAM; Manrique et al 2014). Clearly, the most abundant non-local trade item was jadeite, perhaps the most prestigious mineral resource for the ancient peoples of Middle America.…”